Civil Engineering Reference
In-Depth Information
Table 8.1
Chloride profiles (% of cement) before, directly after and 3 months
reinforcement layer.
Column
Wall section
Wall section
Column
Before the ECE
0 - 2 cm
11.60
7.67
6.60
2 - 4 cm
4.74
1.90
3.35
4 - 6 cm
1.66
1.01
2.37
6 - 8 cm
1.17
0.55
1.97
Directly after the ECE
0 - 2 cm
0.24
0.19
0.07
0.81
2 - 4 cm
0.22
0.56
0.22
0.89
4 - 6 cm
0.38
0.56
0.70
0.70
6 - 8 cm
1.17
1.27
0.96
0.71
3 months after finishing the ECE
0 - 2 cm
0.38
0.93
0.19
0.20
2 - 4 cm
0.34
2.39
0.37
0.22
4 - 6 cm
0.68
2.54
0.97
0.58
6 - 8 cm
1.11
1.40
1.01
1.52
in the concrete from 4.5% directly after the ECE down to 1.8%. Strong
evaporation and capillary suction moved more chloride from the floor slab
into the treated area, as had led to the originally observed high chloride
content.
It was necessary to change the ECE application strategy into either a
two-stage treatment with the conventional repair of the floor slab prior or
right after the first treatment or to use ECE as a supporting application
for a cathodic protection of the floor slabs, which should bring down the
excessive chloride contents to a moderate level and help to save effort for
the instrumentation of the many protection zones that would otherwise be
needed. In this case, the treatment time of ECE could be reduced to max. 2
weeks. A more detailed report about this project is to be found in Schneck
(2005).
8.14 Conclusions
A thorough preparation is essential for a good ECE application, and its
efficiency is variable; some questions remain, e.g. about practical parameters
for the termination of an ECE treatment. Some general conclusions can be
stated as follows:
